Production of ketoesters



Patented Dec. 12, 1950 PRODUCTION OF KETOESTERS Elbert C. Ladd, Passaic, N. J., assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey No Drawing. Application November 9, 1946, Serial No. 708,929

6 Claims. (Cl. 260-491) This invention relates to improvements in the manuiacture of ketones.

It is known (U. S. Patent No. 1,725,362) that when vinyl compounds such as vinyl acetate are heated together with aliphatic aldehydes, that polymeric products result which are gummy or resinous materials. In contrast, I have found that when non-hydrocarbon 2-propenyl compounds having the essential linkage Radical RC O-CH (R')-CH(R")-CIIXY where R is non-tertiary hydrocarbon; P, is hydrogen, methyl, halomcthyl, or halogen; R" is hydrogen, alkyl, aryl, halogen, haloalkyl, or acyloxymethyl; X is nitrogen, oxygen, or halogen; Y is hydrogen or oxygen; or X and Y together is oxygen. Halo and halogen refer to halogen atoms having an atomic weight less than 40, that is, chlorine and fluorine.

More specifically, it may be represented by methyl, ethyl, propyl, butyl, amyl, hexyl, isopropyl, isobutyl, sec-amyl, cyclopentyl, cyclo hexyl phenyl, and functionally aliphatic radicals such as phenylethyl, phenylmethyl, etc.

Representative aldehydes are acetaldehyde, proplonaldehyde, butyraldehyde, isobutyraldehyde, hepaldehyde, cyclohexanal, benzaldehyde, phenylacetaldehyde, etc.

Illustrative of suitable 2-propenyl compounds are allyl alcohol, methallyl chloride, 2-chloromethyl allyl chloride, allyl chloride, ally]. ethyl ether, allyl furfuryl ether, allyl octyl ether, di methallyl ether, diallyl formal, acrclein ethyl acetal, Z-acetoxymethyl allyl acetate, allyl acetate, allyl ethyl carbonate, allyl caproate, allyl laurate, methallyl benzoate, crotyl acetate, cinnamyl acetate, 2-chloroallyl butyrate, methallyl carbamate, methallyl ethyl sulfate, N-allyl phthalimide, N-allyl acetamide, 3-nitr0pr0pene-l, allyl thiethylsilicate, methallyl dimethyl phosphate, etc. I

The preferred 2-propenyl compounds are those 2 of the formula RCH=C(R")CH2X where R, R" and X are as above defined, since these types are more easily available.

Any of the conventional sources of free radicals such as ultra-violet light, may be employed in the method of my invention, although peroxidic compounds, particularly organic peroxides such as dibenzoyl peroxide, diacetyl peroxide, tertiary-butyl hydroperoxide, among others, are advantageous in commercial scale operations and are consequently preferred.

The above formula for the final product in the illustrative equation represents the 1:1 prod-- uct, i. e., 1 mole of-aldehyde to 1 mole of the 2-propeny1 compound, which constitutes a substantial proportion by weight of the reaction product. The reaction product may also include higher boiling ketones of the type formula where n is an integer greater than i.

Appreciable quantities of the compounds or the latter type can be obtained from the reactio: of aldehydes with readily polymerizable penyl compounds such as 2properiyl esters cl polybasic acids, e. g., diallyl phthalate, d'lmeth allyl fumarate and diallyl succinate, and fi li lilil penyl esters of unsaturated monocarbox; Lc acids, e. g., allyl acrylate. This behaviour, how-- ever, is not generally characteristic oi all propenyl compounds containing one or more additional olefinic linkages since others, such as diallyl ether and diallyl formal, react with side hydes to yield largely the OIlB iiO-Oll products.

The reaction of my invention is carried out by heating a mixture of the aldehyde, the propenyl compound and the peroxide in the ence or absence of an inert diluent, and at tea-lperatures suflicient to decompose the percxidio compound, and which are generally in the range of from 0 C. to approximately 140 C. In case of the more volatile aldehydes and penyl compounds, the reactions may be carried out under superatmospheric pressures.

The ratio of the reactants may be varied over a wide range, but it is preferable to emplu; at least one mole of aldehyde per mole of Z propenyl compound, and in practice an excess of the aldehyde, e. g., molar ratio of 2/1 to 15/1, may be employed, if desired. A molar ratio of I 1/1 or greater is particularly desirable for the reaction of aldehydes with the above-mentioned readily polymerizable 2-propenyl compounds, in order to minimize polymerization and other side reactions, which deleteriously affect the yield of the desired ketones. In cases where it may prove inconvenient or impractical to employ a large excess of thealdehydc reactant, the Z-propenyl yields, after evaporation of the compound can be added lncremently to the reaction mixture whereby a substantial excess of the aldehyde is in effect maintained throughout a major portion of the reaction period.

The amount of the peroxidic compound employed as a source of free radicals in my invention varies with the nature of the reactants as well as with the reaction conditions, but amounts in the range of from 1 to 15 mole percent of the Z-propenyi compound, are normally sufiicient. When reaction times are protracted it is often desirable to add the peroxide portion-wise throughout the reaction to ensure the presence of an adequate concentration of free radicals in the reaction mixture at all times.

The reaction is carried out until a substantial conversion of the 2-propenyl compound to the desired ketone is secured. The reaction is then halted by cooling, and the unreacted starting materials are removed by evaporation under diminished pressure. The desired ketone may be then recovered by fractional distillation. In the case of very high-boiling products, fractional crystallization from the reaction mixture may prove more convenient.

The following examples disclose my invention in more detail, all parts being by weight:

EXAMPLE 1 A mixture of 110 parts of allyl'acetate, 500

parts of acetaldehyde, and 8 parts of dibenzoyl peroxide, is heated in an autoclave of 1200 ml. capacity for about 48 hours at about 70 C. After cooling to room temperature, the reaction mixture is removed from the autoclave, the unreacted EXAMPLE 2 Analysis FoundzC, 63.8%; H, 9.18% Theory: C, 62.7%; H, 9.37%

EXAMPLE 3 A solution of 78.5 parts of acrolein ethyl acetal in 450 parts of n-butyraldehyde is heated at 75 C. and atmospheric pressure for 37 hours durin which time 22.5 parts of dibenzoyl peroxide are added in five equal portions. The reaction is completed by heating for 16 additional hours and unreacted starting materials, 34.5 lparts of the diethylacetal of 3-butyropropionaldehyde by fractional distillation; B. P. 101-4" C./6 mm. =1.4352.

Analysis Found: C, 65.83%; H, 10.96% Theory: 0, 65.36%; H, 10.97%

EXAMPLE 4 Analysis Found: 0, 60.09%; H, 8.42% Theory: C, 59.00% H, 8.25%

EXAMPLE 5 To a solution of 98 parts of diallyl ether in 720 parts of n-butyraldehyde at C. and at- 'mospheric pressure are added 19 parts of dibenzoyl peroxide in four, approximately equal, portions during a period of 32 hours. The reaction mixture is further heated for 16 hours, after which unreacted starting materials are distilled oil and the residue is fractionally distilled to yield 28 parts of B-butyropropyl allyl ether; B. P. 96-8 C./6 mm.; 1 .4539.

Analysis Found: C, 70.31 H, 10.57 Theory: C, 70.5%; H, 10.6%

EXAMPLE 6 Analysis Found: c, 65.40%; H, 7.68% Theory: 0, 66.0%; H, 10.0%

It should be noted that'the reaction of poly-2- propenyl compounds with aldehyde according to my invention, as illustrated above in Examples 5 and 6, yields predominantly the unsaturated ketones, even when a considerable excess of the aldehyde is present in the reaction mixture. The diketones from the reaction of 2 moles of aldehyde with 1 mole of the dipropenyl compound are obtained only in minor amounts, if at all.

The various ketones of this invention, including those which are herein new, may be used inter alia as intermediates in chemical synthesis in the production of dyes, perfumes, and pharmaceuticals.

Although my invention has been particularly described as applied to 2-propenyl compounds containing as the hetero atom either oxygen, nitrogen or halogen, the invention may also be apaosaou.

- plied to 2-propenyl compounds containing other hetero atoms, particularly silicon, phosphorus and sulfur. Exemplary of such compounds are ethyl Z-propenyl-phosphonate, allyl triethyl silane and methallyl ethyl sulfide.

While I have shown and described various embodiments of the invention, it is to be understood that the invention is susceptible to those modifications which appear within the spirit of the invention and the scope of the appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. Process of preparing a ketoester which comprises reacting a primary aliphatic aldehyde having the type formula RCHO in which R is a saturated linear hydrocarbon with a, 2-propenyl ester of a monobasic carboxylic acid in the presence of a peroxidic catalyst until said ketoester is formed and isolating said ketoester.

2. The process of preparing ketones which comprises reacting a primary aliphatic aldehyde having the type formula RCHO in which R is a saturated linear hydrocarbon radical with a 2- propenyl ester of a monobasic acid, in the presence of a peroxidic catalyst until said ketones are formed and isolating said ketones.

3. The process 01' preparing ketones which comprises reacting a primary aliphatic aldehyde having the type formula RCHO in which R is a saturated linear hydrocarbon radical with the allyl ester of a monobasic acid, in the presence of a peroxidic catalyst until said ketones are formed and isolating said ketones.

4. The process of preparing ketones which comprises reacting a primary aliphatic aldehyde having the type formula RCHO in which R is a saturated linear hydrocarbon radical with the methallyl ester of a monobasic acid, in the presence of a peroxidic catalyst until said ketones are formed and isolating said ketones.

5. The process of producing 3-aceto-propyl acetate which comprises reacting acetaldehyde with allyl acetate in the presence of a peroxidic catalyst until 3-aceto-propyl acetate is formed and isolating the 3-aceto-propyl acetate.

6. The process of producing S-aceto-propyl acetate which comprises reacting acetaldehyde with allyl acetate in the presence of a diacyl peroxide until 3-aceto-propyl acetate is formed and isolating the 3-aceto-propyl acetate.

ELBERT C. LADD.

REFERENCES CITED The following references are of record .in file of this patent:

UNITED STATES PATENTS Name I C Date Skhl'OW Aug. 23, 1932 OTHER REFERENCES the Number 

1. PROCESS OF PREPARING A KETOESTER WHICH COMPRISES REACTING A PRIMARY ALIPHATIC ALDEHYDE HAVING THE TYPE FORMULA RCHO IN WHICH R IS A SATURATED LINEAR HYDROCARBON WITH A 2-PROPENYL ESTER OF A MONOBASIC CARBOXYLIC ACID IN THE PRESENCE OF A PEROXIDIC CATALYST UNTIL SAID KETOESTER IS FORMED AND ISOLATING SAID KETOESTER. 